Katterfelto arrived at Hull in September 1776 and traveled around Britain until his death in 1799. He performed in London from 1780-84. The widespread flu epidemic of 1782 made him famous as a quack, when he used a solar microscope to show images of microbes he believed were its cause. These "insects" provided him with the catchphrase "Wonders! Wonders! Wonders!" which often headed his advertisements.

He also lectured and entertained using magnetism, electricity, and many other aspects of science. He claimed to have launched the first hot air balloon fifteen years before the Montgolfier brothers, and claimed to be the greatest natural philosopher since Isaac Newton.

Katterfelto was an accomplished conjurer, and hinted that his powers had a demonic origin.

He usually prefixed his name with the title "Dr." or "Col.," and his fame was so great that he was eventually brought to the attention of George III of England, who asked to see this wonder-worker at a command performance.[1]